Yamaha 2002 TDM900, Service Manual

Page: 14 / 475

1-3
FEATURES
GEN
INFO
7
Throttle position sen-
sor
8
Intake air pressure
sensor
9
ECU
10
Atmospheric pressure
sensor
11
Coolant temperature
sensor
12
O
2
sensor
13
Cylinder identification
sensor
14
Crankshaft position
sensor
A Fuel system
B Air system
C Control system
1
Fuel pump
2
Pressure regulator
3
Fuel injector
4
Throttle body
5
Intake air temperature
sensor
6
Intake solenoid
FI SYSTEM
The fuel pump delivers fuel to the injector via the fuel filter. The pressure regulator maintains the fuel
pressure that is applied to the injector at only 294 kPa (2.94 kg / cm
2
, 2.94 bar) higher than the intake
manifold pressure. Accordingly, when the energizing signal from the ECU energizes the injector, the
fuel passage opens, causing the fuel to be injected into the intake manifold only during the time the
passage remains open. Therefore, the longer the length of time the injector is energized (injection
duration), the greater the volume of fuel that is supplied. Conversely, the shorter the length of time the
injector is energized (injection duration), the lesser the volume of fuel that is supplied.
The injection duration and the injection timing are controlled by the ECU. Signals that are input from the
throttle position sensor, crankshaft position sensor, intake air pressure sensor, atmospheric pressure
sensor, intake temperature sensor, coolant temperature sensor, and O
2
sensor enable the ECU to de-
termine the injection duration. The injection timing is determined through the signals from the crank-
shaft position sensor ands the cylinder identification sensor. As a result, the volume of fuel that is re-
quired by the engine can be supplied at all times in accordance with the driving conditions.